As technology has advanced, the need for energy to power technology has increased rapidly. The ability to store energy to power devices has also become increasingly important. One area of an increasing amount of research for energy storage is capacitors with carbon nanotubes (CNTs). The CNTs are typically grown with use of a metal catalyst layer. The metal catalyst layer is difficult to control during deposition. The metal catalyst layer adds to the cost to manufacturing of the capacitor. Unfortunately, the metal catalyst layer typically remains after the growing of the CNTs and negatively impacts performance.
The resistance of the interface between the CNTs and the metal is often the dominant component of resistance in a capacitor. CNTs grown with a metal catalyst layer which results in a high interface resistance due to the metal catalyst layer that remains. The high interface resistance thereby negatively impacts performance. In particular, the high resistance results in poor power performance of the capacitor.
Amorphous carbon also negatively impacts performance. The growth of CNTs using typical processes results in amorphous carbon. The amorphous carbon reduces the accessibility of pores of the CNTs which reduces the surface area thereby impacting performance of the CNTs.